If you haven't already seen EPIC, you should. This 8 minute video is a documentary of future events surrounding the evolution of Google, Microsoft, Amazon and the NY Times. It predicts the establishment of wide social networking via Blogging and fall of printed newspaper media. EPIC is perhaps a bit far on aspects of conspiracy theory, nevertheless its basis is conceivable; even more daunting is the fact that Google is doing many, many other things which aren't even identified here... making one wonder how far it will really go.
What role will private communications (via GMail) play in further establishing dominance in the overall social networking? Probably a lot. The union between blogging and email is already a fuzzy line. Blogger and Gmail have some associations such as publishing via email and email alerts, however the integration is certainly in its infancy. As GMail tools and plugins continue to evolve, we can imagine that the messaging industry at large might be threatened. Of immediate concern are those provisioning towards the consumer experience such as Yahoo, Hotmail, and nationwide ISPs; and in the future could be email service providers and applications such as: Microsoft Exchange, Lotus Notes, Laszlo Systems, Everyone.net, Mail2World, BlueTie, Outblaze, etc.)